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From Norbert Burger <norbert.bur...@gmail.com>
Subject Re: 答复: one table flushes at much smaller sizes than other?
Date Fri, 27 Dec 2013 17:44:55 GMT
Thanks Ted - this config change appears to have reduced quite a bit of the
memstore flushes.

Norbert


On Fri, Dec 27, 2013 at 12:03 AM, Ted Yu <yuzhihong@gmail.com> wrote:

> Raising maxlogs to 64 would give you improvement.
>
> Cheers
>
> On Dec 26, 2013, at 8:35 PM, Norbert Burger <norbert.burger@gmail.com>
> wrote:
>
> > Thanks Ted and Liang.  I do see the "Too may hlogs" line in our logs.
> >
> > We're using the default values for hbase.regionserver.maxlogs = 32 and
> > hbase.regionserver.hlog.blocksize = 64MB, so
> >
> > So given a heapsize = 12GB and lowerLimit = 0.35, does it make sense
> that I
> > should raise maxlogs to be something like 64 or 72?
> >
> > Norbert
> >
> >
> >
> > On Thu, Dec 26, 2013 at 11:03 PM, Ted Yu <yuzhihong@gmail.com> wrote:
> >
> >> Norbert:
> >> What's your setting for hbase.regionserver.maxlogs ?
> >>
> >> Cheers
> >>
> >> On Dec 26, 2013, at 7:51 PM, 谢良 <xieliang@xiaomi.com> wrote:
> >>
> >>> Do you observe some log like "Too many hlogs" before flushing a few
> >>> dozen KB log ?  Just want to double-check it's weather a forcing flush
> >> issue
> >>> or not:)
> >>>
> >>> Thanks,
> >>> Liang
> >>> ________________________________________
> >>> 发件人: Norbert Burger [norbert.burger@gmail.com]
> >>> 发送时间: 2013年12月27日 5:52
> >>> 收件人: user@hbase.apache.org
> >>> 主题: one table flushes at much smaller sizes than other?
> >>>
> >>> Hi folks, we're currently running CDH4.1.2 (HBase 0.92 + patches).
> >>>
> >>> Looking through the logs, I'm seeing that some tables are flushing at
> >> much
> >>> lower size than others (a few dozen KB as opposed to the expected 128
> >> MB).
> >>>
> >>> Looking through some of great case studies like [1], [2], and [3], it's
> >> not
> >>> clear to me why this is happening.  We're using the defaults for upper,
> >>> lower limits (0.35 and 0.40, respectively), and the RS status pages
> show
> >>> that we're only using 25% of our memstore allocation.
> >>>
> >>> Our regions/RS ratio is currently at 60-70.  We do have some other
> tables
> >>> online where column families are skewed heavily sizewise -- could this
> be
> >>> causing other tables in our cluster to flush more frequently than
> others?
> >>>
> >>> Norbert
> >>>
> >>> [1]
> >>
> http://blog.sematext.com/2012/07/16/hbase-memstore-what-you-should-know/
> >>> [2] http://www.ngdata.com/visualizing-hbase-flushes-and-compactions/
> >>> [3] http://gbif.blogspot.com/2012/07/optimizing-writes-in-hbase.html
> >>
>

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